Apparatus for measurement and control



Oct. 7, 1952 c. F. WARD 2,612,902

APPARATUS FOR MEASUREMENT AND CONTROL Filed July 1:5, 1946 m /44 l /44I54 IN VE N T0,?

CHA mas/T \A/Ako Zy 1 flf ATTO NEYS Patented Oct. 7, 1952 APPARATUS ro gumsunsmsnr AND TRO -. 1 Charles F. Ward, Narberth, -Pa., as'signor, by.1 1 6 ass gnments, t c n t uction Finance Corporation, Philadel of theUni edfStates t a, a cor rati n Application July l3, 1946, Serial No.683,296

This invention relates to methods and apps-- ratus for measurementandcontrol purposes, and specifically to pneumatic apparatus especiallydesigned for industrial control and measurement.-

Improv'ed pneumatic apparatus for measures ment and control purposesis'described in the application of Winfield B. Heinz, Serial Number652,525, filed March 7, 1946, now abandoned. The present inventionrelates to transfer meansfa'pplicable to the apparatus of said Heinzapplication and illustrated therein, though of broader application,whereby the final control element can be actuated from the controllerselectively either by manual or by automatic operation. While theprocess is under manual operation under the action of the transfer meansall conditions Within the controller remain'in a continuous state ofbalance so thatwhenever the variable and the control point coincide itwill be possible to transfer the actuation of the final control elementfrom manual to automatic operation .without any change in the positionof the final control element resulting because of the transfer. Transferfrom automatic to manual operation is also accomplished Without changingof thefmal control element.

The broad object of the invention is the pro? vision of transfer meansof the type just indicated.

-This.and other objects of the. invention par, ticularly relatingtodetails of construction'and operation will become apparent from thefollowins description read in conjunction with the acpact n ra ngin whch:

Figure l isaodiagram showi g the el ents of a prefer whe o o de ntrol re bod ing the matters of the present invention;

Figure 2 is a diagram illustrating the connections effected by thetransfer valve whenin its A casing 2 having an external connection at 3to the pressure to be controlled is sealed to a :the. position lowsdownwardly.

l2 and lever 1,4 thebellows is connected to a bellows ii to provide aclosed chamber between the casing and the bellows, so that the bellows lis acted upon externally by the pressure to be controlled. 'A spring 5urges the headof the bel- Through a rod 6, lever 8, link pointer-22which may be of recording type carrying a conventional ink reservoir andpen ar-' ranged to trace a curve on a driven chart as i111istratedin'said Heinz application. An arm 30. of the lever arrang m nt haspivoted torit a link 32 connected to the upper end of a spring 34havns-a link onne onto a relay as h reafter described.

1 A lever 36 having a fixed pivot 38is provided with a cam-following :44engageable in a scroll groove 46 in one side of a cam -plate 48 which isarranged to be rotatably adjustable through, manipulation of 'a suitableknob. A pointer 56 secured to the lever 36 moves relatively to the samechartscaleas the pointer 22.

p A scroll groove 58 in the side of the ,cam' plate 4.8 opposite thescroll groove .45 receives a "camfcllowing pin 60 carried-by a lever 62pivoted at .64 and connected through a link 65 and a spring- 10 to arelay as hereafterdes'cribed.

p {The springs 34 and lo are link-connectedas in ic ed in th d es am o aer 14 c t t tm part of a relay enerall designated 12,}the lever 14 beingprovided with a fulcrum at 75. The relay includes a ham 3 havin a mo abwall constituted by a slack diaphragm 30 of'rela tively large area.Beneath this diaphragm is a second chamber 82, the bottom of which isclosed by a slack diaphragm 8 of relatively small area. Beneath thelever 14 is another chamber'fiili, the upper side of which is closed bya slack ,dia phragm 88 of relatively large area while above thisdiaphragm is a chamber Blithe top of which is closed by a slackdiaphragm 92 of relatively small area. For simplicity of descriptionthere may be assumed that diaphragms and 8-8 have the same area and thatthe'diaphragms $4 and 92 have thesame area though, as will be evidenthereafter, this need not necessarily be the case, if additionalloading'ineans are incorporated in the'relay. All four diaphragms areconnected mechanically to the lever 14 by a pin arrange 'ment indicatedat 94.

By the term slack diaphragm" as used herein there is meant a diaphragmof flexible material which exerts negligible spring action in its displacement.

{The r ht'hand end of the lever 1.4 constitutes a baffle lying between apair of nozzles 9.6 and 98 and arranged to restrict the flows therefromto provide resistances depending upon the bafiie positions.

To provide for rate action, resistances 360 and 362 are joined in seriesto the line 3, resistance 362 opening to the atmosphere. To the junctionof these resistances there runs the connection 364 through theresistance 366 to the capacitance 368.

The chambers 82 and 90 are joined to the ends of the resistance 365.

A removable and reversible plate I is provided with grooves I02 and I04for connecting ports, extending through the base plate of the apparatus,in a pair of alternative arrangements. One of these arrangements isindicated in Figure 1. The nozzle 98 communicates with a port I06, whilethe nozzle 90 communicates with a port I06. A connection I I 0 joins thechamber 86 with a port II2. A connection H4 joins the chamber 80 with aport IIS.

Two ports H6 and E areconnected together and to one end of a pneumaticresistance I22. This resistance, and similar resistances hereafterdescribed may be conveniently referred to as fixed with theunderstanding that this means mechanically unchanged during operation ascontrasted with variable resistances also referred to hereafter.Actually analogy to a fixed electrical resistor is not-strictly existent"when a compressible fluid is used since the resistance value is to someextent dependent upon the pressure drop therethrough. However, fordescriptive and most practical purposes such a resistor may beconsidered fixed even in the sense of maintenance of a fixed value offluid resistance. Two ports I24 and I20 are connected together and to aline I28 connectedto a port I42. A port I30 is connected through a lineI32 and a second line I34 to a chamber I36 constituting a pneumaticcapacitance. The passage I 32 also connects with a reset vent valve I38by which the passage may be connected alternatively either to the atmosphere or to one end of an adjustable resistance I40, the other end ofwhich is connected to the line I28. A port I44 is connected to the endof the resistance adjacentto the valve I38. The reset vent valve I33 isof simple construction, consisting of no more than a screw provided witha valve element I39 movable between two seats, the valve stem beingprovided with a bore open to the atmosphere so that when the valveelement is seated to close off the connection to resistance I40, theconnection I32 is vented to the atmosphere, while when the atmosphericconnection is cut off, as illustrated in Figure 1, connection betweenI32 and I40 is provided.

The ports I42 and I44 constitute apair of ports in a circular array thevarious ports of which are arranged to be selectively joined by atransfer I valve, the construction of which is hereafter described.

For the present, it may be pointed out that besides the ports I42 andI44 in the circular array, there are ports I46, I48, I50, I52 and I54.The transfer valve comprises grooves I56, I 58 and I60 for theselectiveinterconnection of these ports. In Figure 1 these grooves areindicated dotted in the positions assumed during automatic operation.

The port I46 is connected through the line I 62 with the end of theresistance I22 remote from the port H8 and to an automatic pressureregulating means I64 communicating through a line I 65 with a supply ofair under pressure.

The port I48 is connected through the line I66 to a pressure gauge I68.

The port I is connected through a line I10 with a second automaticpressure regulating means I12 connected through a line I13 with thesupply of compressed air.

The port I52 is'connected through a line I14 with the final controlelement, which in the pres- .ent instance is illustrated as adiaphragmoperated .valve I16 in a fluid line I18. As will be evidenthereafter, the pressure delivery line I14 may be connected to any typeof final control element. The ultimate function of the controlleris'toprovide at every instant whatever particular pressure is requiredin the line I14 to control the process in such manner that the pressurein line 3 will-be maintained at a selected constant value.

As an example, the valve I16 might control the 1 flow of fuel throughthe line I18 while the pressure in line 3 may be a function oftemperature or some other variable; or the pressure in line I14 maycontrol an electric current, flow of a chemical reagent or the like, andthe pressure in line 3 may respond to viscosity, liquid level, speed,or'somc other variable. The apparatus is capable of quite generalapplication, the particular applications forming no part of the presentinvention.

The port I 54 is connected through the lines I 00 and I 82 to a gaugeI84 and through the line I88 to a port I61'zcontrolled by the upperpiston I88 of an amplifier. This piston has associated on the same stemwith it a lower piston I92 to define a space in the piston-mountingcylinder to which air','under controlled pressure, is led through thelinesI62 and I94. The pistons I88 and I02 are connected to a lever I96having a fulcrum at I98 and acted upon by a spring 200, the forceexerted by which is adjustable. In the amplifier, a chamber 202 has itsupper side closed by a slack diaphragm 204 and is connected through aline 205 with the end of the resistance I22 which is joined'to the portsH8 and I20; Above the lever I96v is a chamber 208, the lower side ofwhich is closed bya slack diaphragm 2 I0. This chamber 208 is connectedthrough the line 201 to the junction of a pair of resistances 209 and HI, the latter being adjustable. These resistances are in series, withthe free end of the resistance 200 connected to the line I86 and withthe free end of the resistance 2II communicating with the atmosphere. Apin 2I2 connects both of the diaphragms 204 and 2I0 to the lever I96.

The details of the apparatus so far outlined will be understood fromconsideration of said Heinz application but need not be described hereinsince they form no part of the present invention.

The transfer valve cooperating with the ports I42, I44, I46 and I52 andI54 is merely a disc adjustable manually and provided with grooves I55,I58 and I60, the arrangement and dimensions of which are indicated inFigures 2, 3 and 4, these being arranged to join selectively variouscombinations of the ports. As will be indicated in the followingdescription of the operation the transfer valve is adjustable to threepositions for securing respectively manual and automatic operation andbalancing.

The operation of the apparatus so far described will be'best understoodby considering first the conditions which exist when the system is inequilibrium and arranged for automatic operation as indicated inFigure 1. Under these circumstances the measuring element 2 is subjectto ment and its associated stylus 22 and chart scale. As will be evidenthereafter the lever,

has only a very slight movement and-consequently' the stylus pen willmark on the chart a line, the position of which depends solely on thepressure in the line 3.

Under equilibrium conditions the pressures in the chambers 18 and 88 areequal-since-these chambers are connected together-through the resistanceI 46. Likewise the pressures in the chambers 82 and 96 are equal since,011th? assumption of equilibrium, there is no flow through theresistance 366 and consequently nopressure drop across the same, thepressure in the chambers being that existing at the junction of. theresistances 360 and .362: bearin a fixed relationp o the difierencebetween rthe pressure in the line 3 and atmospheric pressure.

The pressure regulator I64 maintains substantially constant pressure atthe right hand end of the resistance I22 and consequently, with thebaffle lever '14 in fixed position a constant flow takes place throughthe nozzle 98 and themessure in the chambers 13 and 86 corresponds'tothe pressure drop through the nozzle.

The constant nozzle pressure is applied through the line 266 to thechamber 262 of the amplifier and equilibrium in the amplifier ismaintained by an assumption of the position of the valve 1488 whichprovides at the junction of the resistances 209 and 21! a pressureapplied to the chamber 268 which maintains the lever I96 in fixedposition. The pressure in the line 1186 being constant a constantpressure is applied to the valve 116' to maintain a constant flowthrough the line H8, or alternatively a constant condition of whateverresponds to the pressure in the line lie.

In view of the equality of pressure in 'xthe chambers of each pair inthe primary-relay it will be evident that equilibrium requires a balanceof the torques exerted on the lever-ls byxthe springs 34 and H1. Thetension of the springdll is fixed by the adjustment of the loam disc :48and as will be evident, the pointer 56 occupies a position which isindicative of, and uniquelyrelated to, the tension of the spring 76. Ifan adjustment is effected to change the tension of the spring 10 andequilibrium is again attained it will be evident that the torquesexerted by the springs .34 and 16 must again balance. Accordingly,whenever equilibrium is attained the pressure in the line 3 must bear adefinite relationship to the tension of the spring 16. construction ofthe grooves in the cam 48, the arrangement of the levers, and theadjustments of the springs, the apparatus is so arrangedthat the pointer.56 and the stylus 22 must always be in coincident positions along thecommon chart scale when the apparatus is in equilibrium. There will nowbe discussed the operations by which equilibrium is attained followingeither anadjustment of the "tension of the spring Hi, i; e.; of

the set-point of the apparatus or a change in the pressure in the line"3. Since the actions are essentially similar it will be assumed thatthe adjustment of the set-point remains fixed and that a pressure riseoccurs in the line 3. In order to simplify the description it will befirst assumed that the resistances 366, 362 and 356 and the capaci- Byreason of the tance1368 are absent and thatcham ers 12 and 6.6 areeither missin or, equivalentl are pen to t e atmosphere. As a matter offact, if th aparatus operated without rate effect his will be the-case.irate .efiect beineuunnecessary in certain instances,

A rise in pressure in he line 3 will raise the link :32 and incr as thetension n the sprin 34. This'action :is a companie y a mo e of thestylus 2:2 away fr m the s t-p int so that the stylus immediately andcontinuously indicates the pressure in t e li h increase tension in thesprin :34 raises the baf l l v 0f the p imary re aypenin t n z i i e 9beyond its previous position and so causing'a substantially immediatedrop in the pressure in the chamber 86. this chamber having a lowcapacita e an being irectly c n ct d W t u s e tial'zi er c d es stanceto th no zl If the connection from the chamber 18 was cut off entirely.it will be evident that equilibrium would be immediatelyattained due tothe fact that the chambers .18 and 36 would .now'be at differentpressures, this equilibrium involving a net zero torque on the lever 14under-theactions of the tensions exerted by the springs .34 and 16 andthe net force resulting fromthe difference in pressures between thechambers-1.8 and 8.6, the bafiie "lever '14 assuming such positionrelative to the nozzle 98 as .to-maintaina sumcient pressure differenceto achieve equilibrium.

Actually, substantially-this does occur immediately upon increase inpressure in-the line 3 since due to the presence of the resistance 1.46and the capacitance provided by chamber 136 the presu e in e chambe Trema ns mo e arily substantially constant. The reset action, :how-

ever, now begins. Since the pressure in the chamber 1.8 is greater thanthe-pressure in the chamber 86 a flow of air from the former to thelatter must take place through the connection H4, port H6. passage I64in bloc}; i-D,6,.port';i36, the body of valve 138 theresistance M6, portI24, passage I62 in block I00 and connection H6. Since capacitance I36,in effect, forms an enlargement of the chamber 18 the drop in pressurein 18 consequent to this flow takes place slowly to an extent de pendentupon the value of the resistance I46 and the size of the capacitanceI36. As the pressure in the chamber 78 drops the downward force on .thelever 14 exerted by the diaphragm 86 is reduced .and consequently thenozzle 68 is still further opened to the extent necessary to produce afurther drop in pressure in the chamber 86 to maintain mechanicalequilibrium of the lever 74. The action accordingly is progressive: astep increase in pressure in the line 3 does not produce afixed pressurein thechamber 86 but causes an initial drop in this pressure followed bya continuing decreasein this pressure at a rate which is continuouslyproportional to the deviation of the pressure in line "3 from itscontrol point, giving rise to aso-called proportional-speed floatingaction.

Ihe'nozzle pressure, 1. e., substantially the'pres sure the chamber 86,is applied to the amplifier illustrated at the lower left in Figure 1and this amplifier delivers to the line 114 a pressure definitelyrelated to the pressure in the line 266 in accordance with theprinciples set forth in Heinz application, Serial No. 561,073, filedOctober so, 1944, the pressureyin the line n4 constituting anamplification of the pressure'in the line 266.

The action of the pressure in the line Ht, by controlling a flow or someother action will tend to correct the deviation of thepressure'in theline 3 from the control point. As a consequence, the pressure in theline 3 will be caused to drop by the operation of the process with aresulting decrease in the tension of the-spring 34 so that ultimatelythere will again be attained mechanical equilibrium of the lever M whenthe pressures'lil and 86 are again equal so that the mechanicalequilibrium of the lever 14 will depend solely on the balancing of thetorques exerted by the springs 34 and 10,. Obviously this can only occurwhen the pressure in the line 3 again returns to the set-point since thesprin 10 has been unchanged. When equilibrium is again attained,however, the pressure existing in the chambers 18 and 86, while equal inthe two chambers, will not-be the same as in the beginning. The bafflewill be displaced slightly from its original position and the pressureabove the nozzle 98 will have changed. As a consequence, the amplifiedpressure in the line H4 will also be different from, what is wasinitially, i. e., it may cause either a greater or less flow through theline H8 or a change in condition of some other controlled medium orcontrolled agent such as may be required under some new demands on thecontrolled system to maintain the pressure in line 3 at the set-point.

While What has just been discussed involved an actual change in positionof the lever 14 it may be pointed out thatthe actual motion of thebaffie end of this lever to secure a full range of change in the nozzleflow is, in fact, very small, being less than 0.001 inch. This movementis so slight as not to affect appreciablythe tensions of the springs 34and 70 so that for all practical purposes the lower ends of thesesprings may be regarded as occupying fixed positions through the entirerange of the apparatus. The result is that the tensions of the springseffectively depend solely on the movements imparted by their upper endswith the result that throughout the entire range of operationsubstantially precise correspondence will exist between the set-point '6and the recording stylus 22 when equilibrium is attained. 3

When rate efiect or action is introduced by the presence of the elementsassociated with the chambers 82 and 93 the action is rather similar butmodified to the extent of some dependence upon the amplitude of thechange in the pressure in line 3. Assume again that the pressure in line3 increases. A proportional increase in pressure will appear at thejunction of the resistances 360 and 362 since their arrangementconstitutes a pressure divider. It may be here noted the only reasonthere is provided a pressure divider is to reduce to some fraction ofthe pressure in line 3 the pressure which is introduced into thechambers 82 and 90, since in many instances the pressure in line 3 maybe quite high and in excess of the pressure which the diaphragms in theprimary relay can withstand without damage. So far as the action isconcerned, the connection of the line 364 could be directly to the line3 and, of course, such connection may be used if the pressure in theline 3 never exceeds a safe limit The increase in pressure in the line364 will now cause a flow of air through the resistance 366 into thecapacitance 368, the pressure in which, at the beginning of the change,will be that which prior to the change existed in the line 364. Theresulting fiow through the resistance 366 will accordingly produce animmediate rise in the pressure in chamber82 as compared with thepressure in chamber 90. The result is that added to the upward force onthe bafile which was caused by the tensioning of spring 34 there is afurther upward force on the baffle resulting from the pressuredifference between chambers 62 and 90, this pressure difference havingthe characteristics pointed out hereafter, it being suificient to stateat the present time that, as will be evident, it depends upon themagnitude of the change in pressure in the line 3. The force so exertedupwardly on the baffle gradually decreases as the pressure in thecapacitance 368 rises. Consequently, while it initially contributes tothe drop in pressure in the chamber 86 its efiect becomes less withtime. Final equilibrium, of course, involves equality of pressure in thechambers Biland 99 and no flow through the resistance 366.

The arrangement which has been described involving the control of thenozzle 98 results in a decrease in pressure in the line I'M when thepressure in the line 3 increases. It is desirable that the apparatusshould be readily adjustable to produce an increase in the pressure inline I74 when the pressure in line 3 increases. This end is achievedmerely by turning the plate I00 upside down whereupon connections areinterchanged so that the nozzle 96 is rendered active, chamber 18becomes the follow-up chamber and chamber 86 becomes the reset chamber,the capacitance I36 being connected directly to the chamber 86 ratherthan to the chamber 18. It may be noted that no reversal of theconnections of the chambers 82 and 90 for rate action is necessary sincethese chambers are arranged to provide forces which are related alwaysin the same fashion to the force exerted by the spring 34.

It will be evident that the various actions resulting from these changesor resulting from decrease rather than increase in pressure in the line3, or resulting from a reset of the set-point are all essentiallysimilar to those described above with mere changes in sign and it will,therefore, not be necessary to describe the various alternatives indetail. A lowerin of the set-point precisely corresponds to a rise inthe input pressure and vice versa.

The rate action which has been described involves the introduction of aninput differential pressure which is substantially proportional, undernormal conditions, to the rate of change of the controlled variable orof some function of it represented by a fluid pressure. Since this rateaction forms no part of the present invention it need not be describedin detail and reference may be made to said Heinz application, SerialNumber 652,525 for further description thereof. Reierence may also bemade to this application for description of the steps involved insetting the parts of the apparatus and adjusting their actions.

It is important in a recorder-controller that means be provided wherebythe final control element can be operated either automatically'by thecontroller itself or manually by the operator. The means provided forthis purpose must be such that the operator can transfer from manual toautomatic operation and, vice versa, without even a transient change inthe pressure delivered to the final control element. In order that thisbe possible it is necessary that the operator be able to compare thepressure which fixes the position of the final control element with thepressure which will be applied to it on transferring from one regime toanother. Before transferring it must be possible to adjust the newsmattepressure to match exactly "the existing valve pressure in orderthat when the'transfer is effected therewill be no change in theposition of the final control element and'thus no upset in the processconditions which are determined by its position. In the presentapparatus these requirements are met through the action of the transfervalve diagrammed in the figures. I V

The automatic position of this valve is indicated in Figures 1 and 4 andits functions have been indicated in the description of the operation bythe references to the various connections. In brief, the ports I42 andI44 are closed off by the valve disc so that the variablereset-resistance MI] is not short circuited. Ports I46 and I48 areconnected so that the gauge I68 indicates the constant pressure whichis. automatically maintained by the pressure regulator I64. v.TheportI50 communicates with the-groove 158 .but no connection isefiectedthereby so that the output of the regulator I12 is not fedtothesystem. Ports I52 and I54'are connected so'that the am' plifieroutput is delivered to the valve I 16..

If it is now desired to pass to manual operation the transfer valve isturned to a balancin position indicated in Figure 3. Ports I42 and M4still remain closed and ports I52 and I54 remain connected so that theoperation continues under automatic control. The change which iseffected by-this position of the valve is merely to connect the gaugeI68 to theYManlial. supply line I70 rather than to the. Automatic?supply line. Accordingly, it is now possible to compare In the positionof Figure. 2 the ports I42 and IE4 are connected, short circuiting. theresetresistance I40 and quickly equalizing the pressures in chambers I8andiifi. Port I46'comrnunicates with the groove I58 but no connectionwith any other part of the system is efie'cted'thereby.

The ports I48, I50 and. I52iarefionnected to gether. Accordingly, thegauge H58 continues to show the-output. pressure of the regulator 112while, at the same time, through the port-I152 there is afforded adirectconnection between the output of the regulator and 'theline I'M.to the valve I'K. Port I5fl ,is cutoff. I

The process is no'wsubject entirely to manual control throughmanipulation or the regulator I12. At the sametimahoweverfthe .automaticparts of the system continue to function, with the exception that theresistance I40 is short circuited so that the samepressures continuouslyexist in chambers I8 and- 86. Accordingly, the parts may be adjusted .or.dismantlecl for repairs or replacements and when. reassembl'ecitheywill attain their normal opetatingconditions.

In the reverse transition from-manuallto' automatic operation, whilemaintainingth'etransfer' valve in the Manual position, the oontrolpointis adjusted to secure-on the' gauge: l-8'4 areading' corresponding tothat on the-gauge IE8; The fact that resistance lit'il is shortcircuite'd insures that no timedelay is involved to permit equalizationof thepressures-i'n chambers-18 and 86. When equality of the gaugereadings-is attained the transfer valve can be'moved directly throughthe Balancing position to the'Auto matic position and automaticoperation will-be T0 resumed. It will be seen that thus a transitionfrom manual to automatic operation may be 6f? iected without disturbinga proper condition which may havebe'eniattained by manual adjustment;that is, the automatic operation is causedto meet the manual adjustment,not the manual adjustment the particular condition which may have beenassumed by the continuousiy operating automatic devices.

' It'inay be noted that the transition between Figures 3 and 4 is merelyone which results in economy of gauges; 1.6;, if gauge Isa-waspermanently connected to line I10, Figure 3 might well represent thevalve position for normal auto mati operation and the setting of Figure4 would be unnecessary. In such case, however, a separate gauge would beprovided .to show the pressure delivered by regulator I64.

As will be evident from the foregoing, not even transient disturbancesare produced during these transrersin the output line I'M;

It will be evident from the foregoing that the recorder-controller whichhas been described is of very general application to any type of systemin which an output pressure can be made to rep? resent a variable whichis to be controlled and control of the variable may beexecuted through apressure delivered by the controller; In fact, ituwill beevident, thatthe input to the system need not necessarily be a fluidpre'ssure butcould well be a force acting directly upon the baffle spring 3.4. Itwill accordingly-be understood that while reference has'been made to aninput pressureof the system, thedescriptions above applied equally to amechanical orelectrical input acting p n the baflle spring :34, 7

While for the sake of simplicity the descriptionhas been based upon theuseot air, it willbe evident that fluids in general maybe used in thesystem and thatanv ases o her tha r may be utilized orevcn liquids whdesir d.- I h case-of liq i s; of course th variou ea ita ces take-theform of in which the rise of liquid level with or Without compression ofgas serves toprovide the necessary pressure ghanges therein. It will, ofcour se ,be evident that the input pressure line may carryliquid-instead of gas.

It will also be evident that by simple reversals oithe parts the-entiresystem may be vacuum rather than pressure operated, the necessarychanges for accomplishing such results being indicatedin Heinzapplication, Serial No. 561,073.

.If .fluidginput is used, the apparatus may be re arded as onetypeofreceiVer for reception of fluidpressure from a transmitter.Pneumatic transmitters for difierent variables may be constructedinaccordance with theprinciples ole.- scribed in said; Heinzapplioation,Serial No. 561,073,- Heinz application, Serial No. 612,505, filed August24;, 1 945 the patent to Arthur E. Increase. John c Wi i s an infi lHeinz, Ne. 2,462,697, issued February 22 me dthe patent to William Melasand Winfield B.

Heinz, 1N0. 2,475,630 issued July 12, 19451.

:What ;I claim and desir to pr t s b L tters Patentis: I

l. Inicombination, means automatically operating to providea variablefluidpressure in ,ac-

cordance with changes ofna variable, manually first mentioned variablefluidv pressure, .a second gauge. and valve means and (connectionsthereto,

7 said valve meanshaving three positions, in one:

of which it provides connection between said automatically operatingmeans and said responsive means to effect automatic operation thereof bythe first mentioned fluid pressure, in the second of which it providesconnection between said automatically operating means and saidresponsive means to effect automatic operation thereof by the firstmentioned fluid pressure and provides connection between the secondmentioned pressure gauge and said manually adjustable means so that bymanual adjustment of the latter the pressure indications of said gaugesmay be equalized, and in the third of which it provides connectionbetween said responsive means, said manually adjustable means, and saidsecond mentioned pressure gauge, so that said responsive means issubject to control by said manually adjustable means, and said secondmentioned pressure gauge indicates the pressure applied to theresponsive means.

2. In combination, means automaticallyoperating to provide a variablefluid pressure in accordance with changes of a variable, manuallyadjustable means for concurrently providing a second fluid pressure,meansresponsive to fluid pressure, a gauge continuously responsive tothe first mentioned variable fluid pressure, a second gauge, and valvemeans and connections thereto, said valve means having two positions, inone of which it provides direct fluid connection between saidautomatically operating means and said responsive means to effectautomatic operation thereof by the first mentioned fluid pressure andprovides connection between the second mentioned pressure gauge and saidmanually adjustable means so that by manual adjustment of the latter thepressure indications of said gauges may be equalized, and in the secondof which it provides connection between said responsive means, saidmanually adjustable means and said second mentioned pressure gauge, andcuts the connection between said automatically operating means and saidresponsive means so that said responsive means is subject to control bysaid manually adjustable means, and said second mentioned pressure gaugeindicates the pressure applied to the responsive means.

3. In combination, means automatically operating to provide a variablefluid pressure in accordance with changes of 'a variable, manuallyadjustable means for concurrently providing a second fluid pressure,means responsive to fluid pressure, a gauge continuously responsive tothe first mentioned variable fluid pressure, a second gauge, and valvemeans and connections thereto, said valve means having three positions,in one of which it provides connection between said automaticallyoperating means and said responsive means to effect automatic operationthereof by the first mentioned fluid pressure, in the second of which itprovides connection between said automatically operating means and saidresponsive means to effect automatic operation thereof by the firstmentioned fluid pressure and provides connection between the secondmentioned pressure gauge and said manually adjustable means so that bymanual adjustment of the latter the pressure indications of said gaugesmay be equalized, and in the third of which it provides connectionbetween said responsive means and said manually adjustable means, sothat said responsive means is subject to control by said manuallyadjustable means.

4. In combination means automatically operating to provide a variablefluid pressure in ac-,

cordance with changes of a variable, manually adjustable means forconcurrently providing a second fluid pressure, means responsive tofluid pressure, a gauge continuously responsive to the first mentionedvariable fluid pressure, a second gauge, and valve means and connectionsthereto, said valve means having two positions, in one of which itprovides connection between said automatically operating means and saidresponsive means to eifect automatic operation thereof by the firstmentionel fluid pressure and provides connection between the secondmentioned pressure gauge and said manually adjustable means so that bymanual adjustment of the latter the pressure indications of said gaugesmay be equalized, and in the second of which it provides connectionbetween said responsive means and said manually adjustable means, sothat said responsive means is subject to control by said manuallyadjustable means.

5. In combination, means automatically operating to provide a variablefluid pressure in accordance with changes of a variable, manuallyadjustable means for concurrently providing a second fluid pressure,means responsive to fluid pressure, a gauge continuously responsive tothe first mentioned variable fluid pressure, a second gauge, and valvemeans and connections thereto, said valve means having three positions,in one of which it provides connection between said automaticallyoperating means and said responsive means to effect automatic operationthereof by the first mentioned fluid pressure, in the second of which itprovides connection between said automatically operating means and saidresponsive means to effect automatic operation thereof by the firstmentioned fluid pressure and provides connection between the secondmentioned pressure gauge and said manually adjustable means so that bymanual adjustment of the latter the pressure indications of said gaugesmay be equalized, and in the third of which it provides connectionbetween said responsive means and said manually adjustable means, sothat said responsive means is subject to control by said manuallyadjustable means, the change of said valve means from its second to itsthird position leaving the operating connections of said automaticallyoperating means in substantially the same operating condition as whensaid valve means was in its first position so that said automaticallyoperating means continues to operate in accordance with changes of thevariable irrespective of adjustments of said valve means.

6. In combination, means automatically operating to provide a variablefluid pressure in accordance with changes of a variable, manuallyadjustable means for concurrently providing a second fluid pressure,means responsive to fluid pressure, a gauge continuously responsive tothe first mentioned variable fluid pressure, a second gauge, and valvemeans and connections thereto, said valve means having two positions, inone of which it provides connection between said automatically operatingmeans and said responsive means to effect automatic operation thereof bythe first mentioned fluid pressure and provides connection between thesecond mentioned pressure gauge and said manually adjustable means sothat by manual adjustment of the latter the pressure indications of saidgauges may be equalized, and in the second of which it providesconnection between said responsive means and said manually adjustablemeans, so that said responsive means is subject to control by saidmanually adjustable means, the change of said valve means from its firstto itsfsecond position leavingthe operating connections of saidautomatically operating means in substantially the same operatingcondition as when said valve means wasinits first position so that saidautomatically operating means continues to operate in accordance withchanges of the variable irrespective of adjustments of said valve means.

7. In combination,;means automatically operating to provide a variablefluid pressure in accordance with-changes of a variable in relation to asetpoint and including means for adjusting a set-point, manuallyadjustable means forces currently providing a second fluid pressure,means responsive to fluid pressure, a gauge continuously responsive tothe first mentioned variable fluid pressure, a second gauge, and valvemeans and connections thereto, said valve means having two positions, inone of which it provides connection between said automatically op--'erating means and said responsive means to effect automatic operationthereof by the rust mentioned fluid pressure and provides connectionbetween the second mentioned pressure gauge and said manually adjustablemeans so that by manual adjustment of the latter the pressureindications of said gauges may be equal.- ized, and in the second ofwhich it provides connection between said responsive means, saidmanually adjustable means, and said second mentioned pressure gauge, sothat said respon' sive means is subject to control by said mam uallyadjustable means, and said second mentioned pressure gauge indicates thepressure applied to the responsive means, said means for adjusting theset point enabling the operator to provide a, fluid pressure output fromsaid automatically operating means equal to the pressure delivered bysaid manually adjustable means prior to a transition from manual toautomatic operation. 1

8. In combination, means automatically operating to provide a variablefluid pressure in accordance with changes of a variable in relation to aset point and including means for adjusting a set point, manuallyadjustable means for concurrently providing a second fluid pressure,means responsive to fluid pressure, a gauge con-'- tinuously responsiveto the first mentioned variable fluid pressure, a second gauge, andvalve means and connections thereto, saidvalve means having twopositions, in one of which it provides connection between saidautomatically operating means and said responsive means to effectautomatic operation thereof by the flrst mentioned fluid pressure andprovides connection between the second mentioned pressure gauge and saidmanually adjustable means so that by manual adjustment of the latter thepressure indications of said gauges may be equalized, and in the sec ndof which it provides connection between said responsive means and saidmanually adjustable means, so that said responsive means is Subject tocontrol by said manually adjustable means, said means for adjusting theset point enabling the operator to provide a fluid pressure output fromsaid automatically operating means equal to the pressure delivered bysaid manually adjustable means prior to a transition from manual toautomatic operation.

F}. In combination, means automatically operating to provide avariablefluid pressure in ac cordance'with changes of a variable in relation toa'set point'and including means for adiusting 1 1 4 asetpoint, manuanyadjustable means for concurrently providing a secondfluid pressure,means responsive togfluid pressure, a gauge continuously responsive'tothe first mentioned variable fluid pressure; a second gauge, andvalvemeans and connectionstheretdlsaid .valve means having'two positions, inone for-which it provides I connection between said automaticallyoperating means and said responsive means to effect automatic operationthereofby the first mentioned fluid J pressure and. provides connectionbetween the "second mentioned pressure gauge and-said manuallyadjustable means so that by manual adjustment of the latter thepressurelindications of said gauges may be equalized, and in the secendof which it provides connection'between said responsive means and saidmanually adjustable means, so that. said responsive means is subject tocontrol by said manually adjustable means, the changeof said valve meansfrom its first to its second position leaving the operating connectionsof said automatically operating means in substantially the sameoperating condition as when said valve means was inits first position sothat said automatically operatingmeans continues to operate inaccordance with changes of the variable irrespective of adjustments ofsaid valve, means, said means for adjusting the set point enabling theoperator to provide a fluid pressureoutput from said automaticallyoperating means equal to the pressure delivered by said manuallyadjustable means prior to a transition from manual to automaticoperationi l0 In combination, means automatically operating to provide afluidpressurein accordance with, changes of a variable, saidautomatically e operating means including a pair'of chambers joined by afluid resistance to give reset action,

manually adjustable means for providing a second fluid pressure, meansresponsive to fluid pressure, a gauge responsive to the first mentionedfluid pressures, second gauge, andvalve means and connectionsthereto,said valve means having two positions, in one of which it providesconnection between said automatically operating ,means and saidresponsive means to'effect automatic operation thereof. and providesconnection, between thesecond mentioned pressure gauge and said manuallyadjustable means .sov

said manually adjustable means, and said second mentioned pressure gaugeindicates the pressure applied to the responsive means, and at'the sametime effects short-circuiting of said fluid resistance so as to maintainequalized the pressures in said chambers.

11 In combination, means automatically operating to provide a'fluidpressure in accordance with changes of avarlable, said automaticallyoperating means including a pair of chambers joined by a fluidresistance to give re'set action, manually adjustable means forproviding a second fluid pressure, means responsive to fluid pressure, agauge responsive to the first-mentioned fluid pressure, a second gauge,and valve means and connections thereto, said valve means having twopositionsjnone of Whichit provides connection between said-automaticallyoperating means and said responsive means to efiect automatic operationthereof and provides connection between the second mentioned pressuregauge and said manually adjustable means so that by manual adjustment ofthe latter the pressure indications of said gauges may be equalized, andin the second of which it provides connection between said responsivemeans and said manually adjustable means, and closes connection to saidautomatically operating means, so that said responsive means is subjectto control by said manually adjustable means, and at the same timeefiects short-circuiting of said fluid resistance so as to maintainequalized the pressures in said chambers.

12. In combination, means automatically operating to provide a fluidpressure in accordance with changes of a variable, said automaticallyoperating means including a pair of chambers joined by a fluidresistance-to give reset action, manually adjustable means for providinga second fluid pressure, means responsive to fluid pressure, a gaugeresponsive to the first mentioned fluid pressure, a second gauge, andvalve means and connections thereto, said valve means having twopositions, in one of which it provides connection between saidautomatically operating means and said responsive means to effectautomatic operation thereof and provides connection between the secondmentioned pressure gauge and said manually adjustable means so that bymanual adjustment of the latter the pressure indications of said gaugesmay be equalized-and in the second of which it provides connectionbetween said responsive means and'said manually adjustable means, andcloses connection to said automatically operating means, so that saidresponsive means is subject to control by said manually adjustablemeans, and at the same time effects short-circuiting of said fluidresistance so as to maintain equalized the pressures in said chambers,the change of said valve means from its first to its second positionleaving the operating connections of said automatically operating meansin substantially the same operating condition aswhen said valve meanswas in its first position so that said automatically operating meanscontinues to operate in accordance with changes of the variableirrespective of adjustments of said valve means.

13. In combination, means automatically operating to provide a fluidpressure in accordance with changes of a variable in relation to a setpoint and including means for adjusting a set point, said automaticallyoperating means including a pair of chambers joined by a fluidresistance to give reset action, manually adjustable means for providinga second fluid pressure, means responsive to fluid pressure, a gaugeresponsive to the first mentioned fluid pressure, a second gauge, andvalve means and connections thereto, said valve means having twopositions, in one of which it provides connection between saidautomatically operating means and said responsive means to eiiectautomatic operation thereof and provides connection between the secondmentioned pressure gauge and said manually adjustable means so that bymanual adjustment of the latter the pressure indications of said gaugesmay be equalized, and in the second of which it provides connectionbetween said responsive means, said manually adjustable means, and saidsecond mentioned pressure gauge, and closes connection to saidautomatically operating means, so that said responsive means is subjectto control by said manually adjustable means, and said second mentionedpressure gauge indicates the pressure applied to the responsive means,and at the same time eflects short-circuiting of said fluid resistanceso as to maintain equalized the pressures in said chambers,said meansfor adjusting the set point enabling the operator to provide a fluidpressure output from said automatically operating means equal to thepressure delivered by said manually adjustable means prior .to atransition from manual to automatic operation.

14. In combination, means automatically operating to provide a fluidpressure in accordance with changes of a variable in relation to a setpoint and including means for adjusting a set point, said automaticallyoperating means including a pair of chambers joined by a fluidresistance to give reset action, manually adjustable means for providinga second fluid pressure, means responsive to fluid pressure, a gaugeresponsive to the first mentioned fluid pressure, a second gauge, andvalve means and connections thereto, said valve means having twopositions, in one of which it provides connection between saidautomatically operating means and said responsive means to effectautomatic operation thereof and provides connection between the secondmentioned pressure gauge and said menually adjustable means so that bymanual adjustment of the latter the pressure indications of said gaugesmay be equalized, and in the second of which it provides connectionbetween said responsive means and said manually adjustable means, andcloses connection to said automatically operating means, so that saidresponsive means is subject to control by said manually adjustablemeans, and at the same time effects short-circuiting of said fluidresistance so as to mainta equalized the pressures in said chambers,said means for adjusting the set point enabling the operator to providea fluid pressure output from said automatically operating means equal tothe pressure delivered by said manually adjustable means prior to atransition from manual to automatic operations.

15. In combination, means automatically operating to provide a fluidpressure in accordance with changes of a variable in relation to a setpoint and including means for adjusting a set point, said automaticallyoperating means including a pair of chambers joined by a fluidresistance to give reset action, manually adjustable means for providinga second fluid pressure, means responsive to fluid pressure, a gaugeresponsive to the first mentioned fluid pressure, a second gauge, andvalve means and connections thereto, said valve means having twopositions, in one of which it provides connection between saidautomatically operating means and said responsive means to effectautomatic operation thereof and provides connection between the secondmentioned pressure gauge and said manually adjustable means so that bymanual adjustment of the latter the pressure indications of said gaugesmay be equalized, and in the second of which it provides connectionbetween said responsive means and said manually adjustable means, andcloses connection to said automatically operating means, so that saidresponsive means is subject to control by said manually adjustablemeans, and at the same time effects short-circuiting of said fluidresistance So as to maintain equalized the pressures in said chambers,the change of said-valve means from its 17 v first to its secondposition leaving the operating connections of said automaticallyoperating means in substantially the same operating condition as whensaid valve means was in its first position so that said automaticallyoperating means continues to operate in accordance with changes of thevariable irrespective of adjustments of said valve means, said means foradjusting the set point enabling the operator to provide a fluidpressure output from said automatically operating means equal to thepressure delivered by said manually adjustable means prior to atransition from manual to automatic operation.

CHARLES F. WARD.

18 REFERENCES orrnn The followingreferences are of record in the file ofthis patent:

Number UNITED STATES- PATENTS Name Date Gorrie Nov. 9, 1937 Eckman Feb.20, 1945 Mason July 12, 1949

